Lyme borreliosis is the most common tick-borne infectious disease in North America, Europe, and northern Asia. The causative bacterial agent of this disease, Borrelia burgdorferi, was first isolated and cultivated in 1982 (Burgdorferi, W. A. et al., Science 216: 1317-1319 (1982); Steere, A. R. et al., N. Engl. J. Med. 308: 733-740 (1983)). With that discovery, a wide array of clinical syndromes, described in both the European and American literature since the early 20th century, could be attributed to infection by B. burgdorferi (Afzelius, A., Acta Derm. Venereol. 2: 120-125 (1921); Bannwarth, A., Arch. Psychiatr. Nervenkrankh. 117: 161-185 (1944); Garin, C. and A. Bujadouz, J. Med. Lyon 71: 765-767 (1922); Herxheimer, K. and K. Hartmann, Arch. Dermatol. Syphilol. 61: 57-76, 255-300 (1902)).
The immune response to B. burgdorferi is characterized by an early, prominent, and persistent humoral response to the end of lagellar protein, p41 (fla), and to a protein constituent of the protoplasmic cylinder, p93 (Szczepanski, A., and J. L. Benach, Microbiol. Rev. 55:21 (1991)). The p41 flagellin antigen is an immunodominant protein; however, it shares significant homology with flagellins of other microorganisms and therefore is highly cross reactive. The p93 antigen is the largest immunodominant antigen of B. burgdorferi. Both the p41 and p93 proteins are physically cryptic antigens, sheathed from the immune system by an outer membrane whose major protein constituents are the outer surface proteins A and B (OspA and OspB). OspA is a basic lipoprotein of approximately 31 kd, which is encoded on a large linear plasmid along with OspB, a basic lipoprotein of approximately 34 kd (Szczepanski, A., and J. L. Benach, Microbiol. Rev. 55:21 (1991)). Analysis of isolates of B. burgdorferi obtained from North America and Europe has demonstrated that OspA has antigenic variability, and that several distinct groups can be serologically and genotypically defined (Wilske, B., et al., World J. Microbiol. 7: 130 (1991)). Other Borrelia proteins demonstrate similar antigenic variability. Surprisingly, the immune response to these outer surface proteins tends to occur late in the disease, if at all (Craft, J. E. et al., J. Clin Invest. 78: 934-939 (1986); Dattwyler, R. J. and B. J. Luft, Rheum. Clin. North Am. 15: 727-734 (1989)). Furthermore, patients acutely and chronically infected with B. burgdorferi respond variably to the different antigens, including OspA, OspB, OspC, OspD, p39, p41 and p93.
Vaccines against Lyme borreliosis have been attempted. Mice immunized with a recombinant form of OspA are protected from challenge with the same strain of B. burgdorferi from which the protein was obtained (Fikrig, E., et al., Science 250: 553-556 (1990)). Furthermore, passively transferred anti-OspA monoclonal antibodies (Mabs) have been shown to be protective in mice, and vaccination with a recombinant protein induced protective immunity against subsequent infection with the homologous strain of B.burgdorferi (Simon, M. M., et al., J. Infect. Dis. 164: 123 (1991)). Unfortunately, immunization with a protein from one strain does not necessarily confer resistance to a heterologous strain (Fikrig, E. et al., J. Immunol. 7: 2256-1160 (1992)), but rather, is limited to the homologous `species` from which the protein was prepared. Furthermore, immunization with a single protein from a particular strain of Borrelia will not confer resistance to that strain in all individuals. There is considerable variation displayed in OspA and OspB, as well as p93, including the regions conferring antigenicity. Therefore, the degree and frequency of protection from vaccination with a protein from a single strain depend upon the response of the immune system to the particular variation, as well as the frequency of genetic variation in B. burgdorferi. Currently, a need exists for a vaccine which provides immunogenicity across species and to more epitopes within a species, as well as immunogenicity against more than one protein.